Patent document 1, i.e., Japanese Patent Application Laid-open No. 2001-74977, illustrates a well-known, conventional mechanical structure of a contact that connects optical fibers. As disclosed in the patent document 1, problems persist in a conventional method for binding a male screw formed at a cable adaptor and a female screw formed at a tube shape body by screwing them together.
A conventional product in the patent document 1 is invented to solve this problem (referred to as a problem 1 0 hereinafter). As shown in the patent document 1, problems persist in the above-described junction structure because too much time and high technique are required to fabricate a machine such as a screw and because forming a smaller device tends to be prevented by introducing the screwing part.